1. Field of the Invention
This invention relates to a rotatable guide sleeve, and more particularly, to an improved rotatable sleeve for guiding wire strands over a rotatable shaft and the like.
2. Description of the prior art
In the prior art, rotatable sleeves for guiding a plurality of wire strands are typified by those used in material cutting machines having a web with a plurality of wires. Rotatable sleeves with grooves for spacing the plurality of wires a predetermined distance from one another are provided in the material cutting machine on a plurality of elongated, parallel, cylindrical rotatable shafts. The plurality of wires between the shafts form a web or wires, wherein a predetermined portion of the web defines a cutting area. Prior art guide sleeves, which are press fitted to the shafts are made of a synthetic material, such as plastics, into which the plurality of grooves are machined. The accuracy of the wire-cutting machine is due to the precise spacing of the wires by the grooves of the rotatable sleeves.
During the cutting operation, the rotatable sleeve is subjected to radial stress by the web of wires which causes transverse expansion and eventually cold flow of the synthetic sleeve into a distorted shape. The dimensional instabilities of the synthetic sleeve result in a considerable deterioration of the cutting accuracy of the material cutting machine after a relatively short period of time. Stress relaxation and fluctuations in operating temperatures may also cause dimensional instabilities in the synthetic sleeve. To maintain the accuracy of the material cutting machine, the synthetic sleeve on the shafts must be periodically changed.
In order to improve the dimensional stability of the rotatable sleeve relatively hard plastics have been used. However, hard plastics have a much lower abrasion resistance than softer plastics and therefore tend to wear out quickly.
For the foregoing and other shortcomings and problems, there has been a long felt need for an improved rotatable guide sleeve.